Segmental grinding wheel



g- 1932- w. w. GREENWOOD SEGMENTAL GRINDING WHEEL Filed May 5, 1930 Witnesses INVENTOR can Wa//oce )1! firm/z wood 7. I 15 v 44% W 2/ ATTORNEY Patented Aug. 9, 1932 UNITED STATES PATENT- OFFICLE.

WALLACE W. GREENWOOD, 0F WORCESTER, MASSACHUSETTS, ASSIGNOR T0 NORTON COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS SEGMEN'I'AL GRINDING WHEEL Application filed May 3,

This invention relates to grinding wheels and more particularly to a grinding wheel made up of a plurality of abrasive segments which are mounted on a rotatable support.

It has been the practice heretofore in the manufacture of grinding wheels in the larger sizes,'such as are used for grinding wood pulp, to build up such wheels of a plurality of abrasive segments which fit together to form a cylindrical surface, These segments are ordinarily made of abrasive grains bonded by means of vitrified ceramic materials in the nature of porcelain or glass, which forms a brittle and weak wheel structure. Owing to the weak structure of the segments it is necessary that these segments be mounted rigidly in position on the support and there held in place by suitable clamping devices to prevent movement during the grinding operation. In accordance with the prior practice, after the segments have been assembled on the'support, a filler of suitable material is introduced into the crevices between the segments to hold them from lateral movement. In the manufacture of these wheels it has been customary for the grinding wheel manufacturer to assemble them in the factory as complete wheel structures and then ship them to the points of use all ready for mounting in the grinding machine. With wheels of this type, it has been-necessary to return the entire wheel structure to the factory for repair when the individual segments have become broken and need replacing. It is therefore desirable that these segments be previously fashioned in the grinding wh'eel manufacturers plant and be shipped out into the field for assembly without necessitating the placing of material in the crevices between the adjacent segments when assembling them on the final support.

It is accordingly one object of this invention to provide a grinding wheel made up of abrasive segments mounted on a rotatable support which is so constructed that it may be easily and properly assembled in the field in a correct grinding position.

A further object is to provide a wheel structure of this type in which the sides of the abrasive segments may be correctly mounted and assembled in a proper grinding relation 1930. Serial No. 449,476.

Greenwood No. 1,469,723 which is particularly adapted for grinding logs into wood pulp. A segmental grinding wheel made in accordance with this invention comprises a rotatable support on which a. plurality of separately removable and replaceable abrasive segments are mounted and secured thereon. in order that the segments may be properly positioned and supported, each segment is provided with one or more permanent lateral preformed facings united firmly and integrally with the rough surface of the segment which are arranged to be placed in juxtaposition with and lit accurately against the lateral and adjacent face of the neighboring segment. To this end, each segment may be provided with a facing molded thereon, as by a casting operation; and for the facing material various substances capable of being molded in position and of giving the desired lateral support to the segment may be employed. The nature of this material will depend on the type of grinding operation, since it is desirable that the material in the grinding zone wear away as rapidly as, or at the same rate with, the abrasive material so as to provide proper support for the wheel c0rners and to keep the crevices properly filled with the facing material. For a pulp grinding wheel, such materials as lead and Babbitt metal may be employed, but for certain grinding operations more brittle materials such as sulfur,or a compound of sulfur and ground coke, known on the market as Lavasul may be used, or such other materials as synthetic resin, known under such names as bakelite,

Y or various other materials, capable of forming a suitable facing on the segment may be em loyed.

eferring to the drawing which illustrates one embodiment of the invention as applied to a pulp grinding wheel and in which like reference numerals indicate like parts:

Fig. 1 is a fragmentary sectional view of one embodiment of the invention; and

Fig. 2 is a perspective view of an abrasive se ment.

n a grinding wheel of this type, a plurality of abrasive segments 10 are removably mounted on a drum 11 or other suitable rotatable support and they are clamped in a grinding position by means of wedge blocks 12 which engage beveled clamping shoulders 13 within grooves 14 between the segments. In this type of wheel a shoe 16 of suitable material, such as lead or Babbitt metal, is loosely placed on or is integrally and permanently formed on each shoulder of the abrasive segments in order that the wedge blocks 12 may make a proper contact therewith and not crush the abrasive material. Similarly, a shoe 18 of suitable material, such as babbitt or lead, is located on the inner peripheral supporting face of each segment adjacent to its outer corner, as illustrated, or it may extend across the entire bottom portion of the segment. This shoe is formed integrally with the segment and has a partial cylindrical surface 19 which is shaped to fit accurately against theouter peripheral surface 20 of the support and thereby serves to seat the segments correctly thereon. The two shoes may be cast on the segment in suitably shaped molds or otherwise shaped so that they will fit together.

In the construction illustrated, the clamping blocks 12 have beveled faces 21 engaging the upper surfaces of the shoes 16 on the beveled clamping shoulders 13 of the segment, whereby the wedge blocks may be properly aligned with the shoulders'of the two ad acent segments and so serve to clamp them removably in position on the support and yet hold them both rigidly and securely in place. Each wedge block is adjustably secured to the drum ll by means of bolts 22 and nuts 23 which engage a collar 24 resting against the inner surface of the drum. The bolts 22 are screw threaded at their upper ends into the wedge blocks 12 and the lower ends pass through holes in the drum and are secured there y the nuts 23 engaging the under side thereof. If desired the bolts 22 may be made of an elastic material which will permit expansion of the wheel due to temperature changes. Various other constructions may obviously be employed to fastenthe segments in position on the support.

In order to provide, the facings on the inner sides of the wheel, it is proposed to mold permanent lateral faces 26 of such ductile material as lead or Babbitt metal on the adjacent lateral faces of the segments, and this is done preferably by casting the material in a mold enclosing the face of the segment and which is shaped to fit the opposed surface of the adjacent segment. This metal facing 26 will enter the surface pores and adhere to the rough surface of the segment to become an integral part thereof. The outer surface 28 of this facing is substantially radial and it is made smooth surfaced in order that it may afford-a plane contact surface which is adapted to fit accurately against a similar plane lateral facing on the contiguous face of the adjacent segment and contact rigidly there with.

In order to aid in securing the facing 26 to a segment face and to hold it properly in position, the sides of each segment may be provided with grooves 30 suitably shaped to interlock with the facing. If such materials as sulfur are used, they may likewise be melted and cast on the segment faces. If a material such as a resin is employed, it would be softened and buttered onto the segment and then heat set in a suitable mold, or otherwise caused or permitted to harden. It is to be understood that the method of forming the facing and providing the desired shape will be suitable for the material chosen for the facing. The main feature of the invention is involved in the provision of a facing which is fastened to the segment and makes intimate and full contact therewith for distributing pressure received by the facing to a considerable portion of the abrasive body and which has a surface capable of fitting with sufficient accuracy against the adjacent segment, or a similar preformed contiguous facing thereon, so as to .provide a filled crevice to support the segment against lateral pressure tending to break it when mounted in an assembled wheel structure. Ordinarily, it is preferred that the facing be located on each side of the segment so that each facing will engage the accurately formed facing surface on the adjacent segment; but in certain cases it is sufficient to provide but one facing in each crevice between two segments, in which case the act of clamping the segments in position will serve to draw the facing into firm contact with the abrasive material of the adjacent segment.

Itwill be apparent that this invention provides a way whereby the segments may be correctly fitted on their support without the necessity for subsequently casting a filler in the crevices between the segments to prevent lateral motion. It will also be understood that in a grinding wheel construction of this type, one may utilize either a single row of segments, as may be employed for a metal grinding wheel, or several rows of segments mounted on a drum, in accordance with the showing of the Greenwood patent. In view of the above disclosure, various modifications of this invention will be apparent to one skilled in the art and these are considered as embodied to the above invention and ex pressed in the claims appended hereto.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding wheel comprising a rotatable support, a plurality of abrasive segments mounted thereon, each segment having a permanent lateral facing preformed integrally therewith --.which has a surface shaped to fit accurately against a lateral face of an adjacent segment, and means to clamp the segments removably in position on the support, said segments being separately removable and replaceable without afiecting the facing.

2. A grinding wheel comprising a rotatable support, a plurality of separately removable abrasive segments mounted thereon, each segment having a clamping shoulder and a preformed facing integral with 2. lat eral face. which has a substantially radial surface arranged to contact rigidly with the contiguous lateral face of an adjacent seg ment, clamping members engaging said shoulders and means for adjustably fastening said members to the support.

3. A grinding wheel comprising a rotatable support, a plurality of abrasive segments thereon, each segment havin a pre formed facing integral therewith w ich fits accurately against a similar preformed contiguous face of the adjacent segment, said contiguous faces being substantially radial planes in the assembled wheel and aligned to provide an accurate contact and a rigid I wheel structure, and clampingblocks to hold said segments removably positioned.

4. A grinding wheel comprising a rotatable support, a plurality of abrasive segments mounted thereon, each segment having permanent lateral facings of ductile metal preformed integrally therewith which provides plane surfaces shaped to fit accurately against similar plane lateral facings of the adjacent segments, and means to clamp the segments removably in position on the support, said segments being separately removable and replaceable without affecting their facings.

5. A grinding wheel comprising a rotatable support, a plurality of abrasive segments removably mounted thereon and forming a grinding surface, each segment having a permanent lateral facing preformed integrally therewith, arranged to engage a lateral face of an adjacent segment, a beveled clamping shoulder provided with a shoe inte al therewith for engaging a clamping device and an inner supporting face having a shoe integral therewith which is shapedto fit against the peripheral surface of said support and form a seating surface for mounting the segment ent comprising a body lateral facing preformed integrally with one of said side surfaces which has a lane surface arranged to engage a lateral ace of an adjacent secgment when mounted on the supporting b0 y.

7. An abrasive segment comprising a body of ceramic bonded abrasive grains having an outer cylindrical grinding surface opposed side surfaces and a clamping shoulder, a shoe integral with said shoulder for engaging a clamping device, a shoe formed integrally on the bottom of the segment which is s aped to fit against the peripheral surface of said support and form a seating surface for mounting the segment thereon, and a permanent lateral facing preformed integrally with one of said side surfaces which has a surface shaped to accurately engage similar preformed facings on the adjacent segments an assembled structure. a

8. An abrasive segment comprising a body of ceramic bonded abrasive grains having an outer cylindrical grinding surface opposed side surfaces having beveled clamping shoulders, a shoe formed integrally on each of said shoulders for engaging a clamping device, shoes formed integrally on the bottom of the segment which are shaped to fit and seat against a supporting drum, and ermanent lateral facings on the opposed si e surfaces which are shaped to accurate] engage similar facings preformed on t e contiguous faces of the adjacent segments when mounted in an assembled wheel structure.

Signed at Worcester, Massachusetts, this 30th day of April 1930.

WALLAoii W. GREENWOOD. 

